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Associate Professor Graham Nicholson, from the University of Technology Sydney, talks about the venoms in Australian spiders and how venom components are contributing to the development of new ecofriendly insecticides.

Spiders help keep the ecosystem in check, largely preying on members of the most group of animals on Earth - insects. While spiders (and especially in Australia) tend to be quite widely feared, only a small fraction of the 40,000 spider species in the world is potentially dangerous to humans.

Even in Australia, there are really only two that have components in their venom that are highly toxic to humans: funnel webs and redbacks. In fact, it is just an unfortunate accident that the toxicity of some venoms spills over to humans since typically the venoms of spiders are specifically toxic to insects. It is this aspect that forms the basis for new research into insecticides.

Many of our commercial insecticides persist in the environment and are toxic to other organisms. Fish for instance are often significantly affected due to the run off into streams and lakes. Therefore an insecticide that is selective only to insects would have a range of environmental and biological benefits. The research at UTS has so far has isolated two different groups of toxins that are highly insect selective and that act on novel targets (ie not those acted on by our current insecticides) in the insect nervous system, making it harder for the insects to develop resistance to them. These are currently in advanced stages of development for marketing as commercial insecticides.

Graham Nicholson's research group works in collaboration with other research groups around the world including Belgium, France, Mexico, Singapore, USA. Apart from developmentof potential insecticides, some groups are focussing on producing analgesic-type compounds for human use.

Perhaps not surprisingly there are a number of urban myths about the toxicity of Australian spiders. One is that the white-tailed spider gives horrendous bites that break out at regular intervals with tissue destruction. This is indeed an urban myth. Studies have shown that no one has developed this flesh eating infection from a white-tailed bite. The most likely explanation of these infections is that bacteria in the environment enter the skin through scratches or cuts. Often the occurrence is linked to people after they have been working in the garden and have been exposed to a range of soil living bacteria and it is these oreganisms that are responsible for the infection.

Another is that spiders are aggressive. In almost all cases spiders are defensive in their posture and steer away from direct contact with humans. When cornered, funnel webs do take what appears to be an aggressive pose, rearing up on their hind legs. However this is a defensive mechanism, because they can only use their fangs if they can strike downwards.